Workaround for flickering lights

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2trackin

New member
I'm aware of the canbus flickering light thing. After running my rock lights relay with the factory fog light switch. Everything works fine till I start the engine and get flickering. Did a simple Google search and found why. For the time being I do not want to start running wires through the firewall and start drilling and cutting for switches or a switch panel till I have a better idea of what my final accessory layout may be.
I thought I read of some work around for this using resistors or capacitors in line of that for light feed to the relay that will stop the flickering.
Thanks in advance for any input on this.

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OverlanderJK

OverlanderJK

Resident Smartass
So you have your rock lights hooked up to your factory fog switch but it still flickers? If it's done right it shouldn't. My light bar doesn't flicker ever and it is hooked into the factory fog switch with a relay.
 
jnabird333

jnabird333

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The fog lights are a part of the CANBUS circuitry. If you tap into the fog "hot" wire to trigger a relay, it will cause relay chatter and flickering of whatever you are activating. Here is a circuit that will help correct this.

CANBUS_FIX.png
 
C

chuckt62

Member
From my experience any PWM on the fogs hasn't caused any relay chatter.

If it is chatter it will be very obvious with the contacts clicking.
 
jnabird333

jnabird333

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chuckt62 said:
From my experience any PWM on the fogs hasn't caused any relay chatter.

If it is chatter it will be very obvious with the contacts clicking.
Click to expand...

I tested 5 brands of relays and all of them chattered when I tapped a PWM Canbus hot on my 13.

It's more of a buzz, but yes it's obvious.


Edits to correct the damn auto correct

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2

2trackin

New member
jnabird333 said:
The fog lights are a part of the CANBUS circuitry. If you tap into the fog "hot" wire to trigger a relay, it will cause relay chatter and flickering of whatever you are activating. Here is a circuit that will help correct this.

CANBUS_FIX.png
Click to expand...


Awesome, thanks. Exactly what I was looking for. I just need to add the 1N5400 Diode and looks like I should be all set.
Where do I aquire this? Radioshack still carry this stuff?
 
jnabird333

jnabird333

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2trackin said:
Awesome, thanks. Exactly what I was looking for. I just need to add the 1N5400 Diode and looks like I should be all set.
Where do I aquire this? Radioshack still carry this stuff?
Click to expand...

Yes, I got everything from the shack..... But it's the capacitor that actually corrects the issue. The diode just forces it's charge to drain through the coil of the relay and not back into the CANBUS so don't leave it out.

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C

chuckt62

Member
jnabird333,

BTW, the diode in your diagram is connected bass-ackward. The triangle/arrow (anode) side should connect to the hot tap. The line/stripe (cathode) should connect to the relay, 85.

Or a better way is to connect the diode across the relay coil with the cathode on the hot tap, 85 and the anode on the other pin, 86.
 
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jnabird333

jnabird333

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chuckt62 said:
jnabird333,

BTW, the diode in your diagram is connected bass-ackward. The triangle/arrow (anode) side should connect to the hot tap. The line/stripe (cathode) should connect to the relay.
Click to expand...

Nope, it's correct. Again, the point of the diode is to force the capacitor to discharge through the really coil. If it were biased the other way it wouldn't do this.

I have made about a dozen of these.... All work great.


EDIT... I think your right... hell I can't think at the moment, I'll have to check this in the morning. I have made several of these though????
 
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2

2trackin

New member
jnabird333 said:
Yes, I got everything from the shack..... But it's the capacitor that actually corrects the issue. The diode just forces it's charge to drain through the coil of the relay and not back into the CANBUS so don't leave it out.

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Click to expand...

Oh geez. I didn't even see it. I'm looking at it on a small phone screen.
I'm going to try and get to this tomorrow and try it out.

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R

rdreng

New member
What ChuckT62 mentioned is correct. The diode is backward as shown in the schematic. This diode prevents any current from flowing back into the Jeep electronics (performs an isolation function) and isolates your capacitor. A diode across the relay coil is also a good idea (it clamps any voltage spikes generated by the relay coil).
 
OverlanderJK

OverlanderJK

Resident Smartass
I have absolutely zero chatter with my light bar and I just wired in a relay. None of that other crap. In fact sharkey has done the same on other peoples jeeps.
 
Sharkey

Sharkey

Word Ninja
OverlanderJK said:
I have absolutely zero chatter with my light bar and I just wired in a relay. None of that other crap. In fact sharkey has done the same on other peoples jeeps.
Click to expand...

Yep, no chatter or flicker on the lights I have installed using a relay and the factory wiring as a trigger. Without a relay in the mix though, I got some weird strobe effects after the light was turned OFF.
 
jnabird333

jnabird333

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Sorry for the delayed reply. I was pretty distracted last night (shouldn't really have been on the forum) and had a very busy day. Apparently I was inebriated when I made the diagram too as diode is in fact polarized incorrectly.

Before you go to the trouble of making this up, make sure you are fighting the PWM and not another issue. While I had relay chatter, it seems others haven't so it's worth a second look. It is also important to note that I use my high beam hot and reverse hot as triggers and both needed the circuit above (correctly made of course). I did find a PWM signal on the fogs when testing, but didn't actually try to use the hot to run a relay. I assumed it would be needed since the PWM was present. Knowing that it is present I would want the circuit regardless of relay chatter or not, we are only talking about $2 and some time to protect the CANBUS and clean the voltage to the relay. just my :twocents:
 
2

2trackin

New member
Well I did a test fit rewire using your diagram. Works perfectly now.
Just need to do a permanent hook up and I'll be good to go.
Thanks again!

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pvanweelden

pvanweelden

New member
I am glad you got the flickering figured out! Jnabird, chuckt, and rdreng= you guys rock! :thumbup:

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